This invention relates to novel compounds as a component of liquid crystal mixtures and liquid crystal compositions containing the same.
Liquid crystal display elements utilize the optical anisotropy and the dielectric anisotropy of liquid crystal substances, and are classified into those of various modes such as TN type (twisted nematic type), DS type (dynamic scattering type), guest-host type, DAP type, etc. depending on their display modes, and the properties of liquid crystal substances suitable to the respective uses vary. It is common to any of liquid crystal substances that they are stable to moisture, air, heat, light, etc., and those having a mesomorphic range as broad as possible, around room temperature, have been sought. Up to the present, however, any single compound which satisfies such conditions has not been found; hence liquid crystal compositions obtained by blending several kinds of liquid crystal compounds and non-liquid crystal compounds have been used.
Namely it has generally been required for liquid crystal compositions used for display elements that not only they should have a broad mesomorphic range including practical temperatures, but also they should have low viscosities, and further they should impart to display devices, low threshold voltages, short response times, and small electric power consumption.
British Pat. No. 1,473,990 discloses 5-alkyl-2-(4-cyanophenyl)pyrimidines as liquid crystal compounds having a great dielectric anisotropy, but even these compounds do not satisfy all of the above conditions required as a material for liquid crystal display elements.
The object of the present invention is to provide novel compounds which, when added to liquid crystal substances, can improve some characteristics required for the resulting liquid crystal compositions.